Hydraulic pump.



J. W. NELSON.

HYDRAULIC PUMP APPLICATION FILED JAN. 31, 1908.

909,647. Patented Jan. 12, 1909.

3 SHEETS-$11331 1.

ATTORNEY THE NORRIS PEIERSCO" WASHINGTON, n. c.

J. W. NELSON.

HYDRAULIC PUMP. APPLICATION TILED JAN. 31, 1903.

Patented Jan. 12', 1909. BASKETS-SHEET 2.

Y ATTORNEY J. W. NELSON.

HYDRAULIC PUMP.

APPLICATION FILED JAN. a1, 1908 909, K Patented Jan. 12, 1909.

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'UTED STATES PATENT orrrcn.

JAMES W. NELSON, OF NEW YORK, N. Y.

HYDRAULIC PUMP.

To all whom it may concern:

Be it known that I, JAMES W. NELSON, a citizen of the United States, anda resident of the city of New York, borough of Brooklyn, county ofKings, and State of New York, have invented certain new and usefulImprovements in Hydraulic Pumps, of which the following is aspecification.

This invention relates to hydraulic pumps, with more particularreference to the valves of a device of this character and means fortheir control.

\Vith what is known as a double-pump jack-that is, a jack having twopumps of different capacities, both being utilized for purposes of speedto bring the ram up to the point where it receives the full weight ofthe load, after which the larger of said pumps is rendered effectivelyinoperative, whereby speed is sacrificed for increased power under thewell-known principles of hydrostaticsa total of five valves was for along time considered essential. As is well known, the valves aredoubtless the weakest parts of a device of this character, being almostinvariably the first parts to get out of order or repair, frequentlycausing trouble and delay, and necessitating dismemberment of the jackfor their removal for repair or replacement. With this idea in mind, thetotal number of valves necessary for the successful operation of adouble-pump hydraulic jack, was ultimately reduced to four, and morerecently (as shown and described by me in an earlier patent, No.874,698, dated December 24, 1907) to three valves, which, when free toperform their automatic functions, rendered both of the pumpseffectively operative, but which were subject to manual control toeffect, first, rendering one of said pumps inoperative to sacrificespeed for power in the manner referred to, or, second, to render both ofsaid pumps inoperative, as might be desirable, among other conditions,when the pumps were driven by power and it was desirable to temporarilycease the application of increased pressure without checking thepump-actuating means, or, third, to open all three of said valves andthus relieve the pressure in the ram or pressure chamber and open anunobstructed passage from said chamber back to the reservoir or othersource of liquid supply.

The present invention primarily contem- Specification of Letters Patent.

Application filed January 31, 1908.

Patented Jan. 12, 1909.

Serial No. 413,544.

plates still further reducing the number of valves necessary for theproper operation of a double-pump hydraulic jack to two, these twovalves, under normal conditions rendering effective the operations ofboth pumps, but being provided with controlling means operable, first,to render ineffective the stroke of one of the pistons, or, second, torender ineffective the strokes of both pistons, or, third, to relievethe pressure in the pressure chamber and permit of the lowering of theram.

By reference to my earlier patent of De-- cember 24, 1907, aforesaid, itwill be seen that when both pumps are efiectively operative, the middleof the three valves performs no useful function. In fact, under theseconditions, the double-pump jack is really nothing more than asingle-pump jack the piston of which has an effective area equal to thecombined effective areas of the two pistons shown and described.Therefore, when both of said pistons are effectively operative, themiddle valve of the series of three shown and described may beeliminated. It will now be apparent that if the upper valve were bodilyand operatively transferred to a point in the valve-bore between theducts to the pump chambers and at the same time leave open a passagefrom the upper pump chamber to the cource of liquid supply, the lowerand smaller piston alone will be effectively operative, the result beingthe same as that occurring when the upper of the series of three valvesis held off its seat.

' The principal object of this invention is the provision of means,under easy control, for changing the location of the upper of two valvesin the valve bore to a point when it checks back flow from the lower orsmaller pump alone, instead of from both pumps, and this without closingthe passage between the upper or larger pump and the source of liquidsupply. In this manner the middle valve of the series shown anddescribed by me in the patent aforesaid may be eliminated, and I willhave a doublepump jack with but two valves, yet which is capable ofperforming every useful function required of this type of device.

My invention will be more readily understood. by reference to theaccompanying drawings, forming a part of this specification, in whichFigure 1 is a central sectional elevation of what is known as thehorizontal type of hydraulic jack embodying my invention; Fig. 2 is acentral'sectional elevation of a so-called vertical type of jackembodying the same invention, and Fig. 3 is a sectional view of thepumpblock, valves and valve controlling means shown in Fig. '1, on anenlarged scale, with the upper valve in its changed location.

lteferring now to the drawings in detail, and first to the constructionshown in Figs. 1 and 3, numeral 11 refers to the shell or casing of aso-called horizontal type of jack, which preferably includes thecylinder for the ram, but as these members form no part of the presentinvention they are not illustrated in the drawings. Preferably removably mounted in the base of this shell or casing 11 is the pump-block12, closing and sealing the openin through which it is inserted andbeing of such dimensions that the chamber 13 is provided above the samewhich constitutes a storage reservoir for the liquid employed andprovides space for the interior pump-operating mechanism.

The pump-block 12 is provided with a central pump-bore which comprisesan upper portion 14 of relatively larger diameter and a lower portion 15of relatively smaller diameter. A piston rod 16 is provided with a head17 in which a socket 18 is adapted to receive a knuckle 19 at the end ofa short arm 20 fixed upon the rockshaft 22 which has suitable hearingsin the shell or casing 11. This shaft 22 projects to the exterior ofsaid casing, where it is connected with a suitable operating lever, orother actuating means, not shown in the drawings. Upon the piston-rod'16 is mounted a piston 23 snugly fitting Within the portion 14 of thepump-bore, while an extension 24 of said pistonrod carries the smallerpiston 25 snugly fitting within the lower portion 15 of said pump-bore.The pistons are preferably provided with suitable packing, which being acommon and well known expedient, is not shown in the drawings. Thepump-block 12 is provided with another longitudinal bore 25, whichextends completely through said pumpblock, the lower end thereof beingclosed and sealed by means of the screw-cap 26. Snugly fitting withinthe upper portion of this bore 25 and slidable therein, is the tube 27,the upper end of which is provided with the flange 28 between which andthe top of the pump-block 12 a suitable spring 29 is under compression.The lower end of the tube 27 provides a seat for the valve 30, whichpreferably has a guiding stem 35 extending upwardly in said tube. Whensaid tube 27 is in its normal or most elevated position. the lower endthereof is just above a duct 32 which connects the bore 25 with thebottom of the chamber 14 below the larger piston 23. Below the duct 32,the diameter of the bore 25 is abruptly increased, for a purpose whichwill hereinafter be made clear, and in the lower end of this enlargedportion of the bore 25, I prefer to insert a removable cylindricalvalveplug 33, the lower end of which provides a seat for the valve 34which has a stem 35 projecting upwardly nearly but not quite to thepoint where the diameter of the bore 25 changes. Just above the valve34, a duct 36 provides communication between said bore 25 and the bottomof the chamber 15 below the smaller piston 25 The valve 34, if desired,may be spring-seated, as shown.

Near the lower end of the tube 27 is provided the lateral and preferablylongitudinally elongated aperture 37. In the position indicated in Fig1, this aperture, 0bviously, serves no useful purpose, but when saidtube 27 is depressed, in the manner hereinafter described, this aperture37 is adapted to register with the duct- 32 and open a passage from thepump-chamber 14 to the interior of said tube 27 above the valve 30.

Loosely fitting over the upper and preferably reduced portion of thepump-block 12, is the sleeve or collar 38 provided at its upper end withan exterior flange 39 and a preferably somewhat wider interior flange40. This sleeve 0r collar 38 is normally re tained in its elevatedposition by means of a suitable spring 41 in compression between theexterior flange 39 and the shoulder 42 on said pump-block. The interiorflange 40 projects over and upon longitudinal movement of said collar isadapted to engage the flanged upper end of the tube 27.

Suitably journaled in the shell or casing 11 is the shaft 43 at theinner end of whichis suitably mounted a cam 44 in coi perativepositional relation to the exterior flange 39 on the sleeve or collar38. This shaft 43 is rotated by means of a lever 45, on the outside ofthe casing, and by such rotation the cam 44 may be operated to depressthe collar 38 against the action of the spring 41, the latter serving toreturn said collar to its normally elevated position when the same isrelieved of theovercoming pressure of said cam.

It will be apparent that the cam 44 may be operated to depress thecollar 38, carrying therewith the tube 27, until the aperture 37 in theside of said tube registers with the duct 32. In such position, thevalve 30 has been depressedwith said tube to a plane slightly below thetop of the enlarged portion of the bore 25, but does not contact withthe stem 35 of the valve 34, the latter being free to perform itsfunctions in the usual manner, as shown in Fig. 3. Further rotation ofthe. cam. 44 will continue downward movement of the tube 27 until thelower end of the longitudinal groove 47 in said tube clears the shoulder50, where the diameter of the bore 25 is increased. At the upper end ofthis longitudinal groove or channel 47 is a communicating annular groove46 which includes the aperture 37 in the tube 27. In this position, thevalve 34 remains seated, under the excess of pressure below the same,but an open passage has been provided from the chamber 15 under-- neaththe lower piston through the lower portion of the bore 25, the grooves47 and 46, the aperture 37 and the upper portion of the bore 25 to thesource of liquid supply. The aperture 37 being longitudinally elongated,as stated, the passage described from the chamber 14 to said source ofsupply remains open. Still further rotation of the cam 44 will effectengagement between the valve 30, and the top of the stem 35 of the valve34 and force the latter off its seat, thus opening a passage from thepressure chamber to the source of supplythe passages from the pumpchambers to the same point remaining open.

To provide for the entrance of liquid to the tube 27, and, therefore tothe pump chambers, and at the same time to avail my self of the maximumcapacity of the reservoir, I have shown an aperture 49 in the wall ofthe pump-block 12 with which a corresponding aperture 48 in the tube 27is adapted to register. IVhen the device is to be used in a horizontalposition only, it will be seen that the tube 27 alone may be aperturedat a point above the top of the pumpblock, but when the device is usedin a vertical position, the provision of the lower registeringapertures, as shown, renders available a larger volume of liquid if froma contained source of supply.

It will now be apparent that with the various parts in the positions ofadjustment indicated in Fig. 1, upon the upstroke of the pistons, liquidwill flow from the reservoir 13 above the pump-block, or from othersuitable source of supply, through the aperture 49 in said block and theregistering aperture 43 in the tube 27, into the bore 25 and thence pastthe valve 30, which it unseats, into the chambers 14 and 15 below therespective pistons. Upon the downstroke of said pistons, the excess ofpressure will. seat the valve 30 and unseat the valve 34. the liquidbeing forced into the chamber 51 in the bore 25 below the valve 34 andthence through the duct 52 and its connections to the ultimate pressurechamber. hen the ram has been raised to the point where it receives thefull weight of the load, or it is otherwise desired to utilize thepressure of the smaller pump only, the cam 44 is rotated in the mannerdescribed to depress the tube 27 until the aperture 37 registers withthe duct 32, in which position, as explained, the valve 30 isnon-interferent with automatic action of the valve 34. It will now beapparent that upon the up-stroke of the piston, the liquid which entersthe chamber 14 through the aperture 37 above the valve 30 (see Fig. 3)will, upon down-stroke of said piston flow back through said apertureand to the source of supply. The liquid which enters the chamber 15below the smaller piston, which in its flow has unseated the valve 30,will upon clown-stroke of said pistons, seat said valve 30 and be forcedpast the valve 34 to the pressure chamber. Under these conditions, itwill be apparent, the lower pump only is effectively operative. Torender both pumps inoperative without, however, relieving the pressurebelow the valve 34, rotation of the cam 44 is continued until the bottomof the groove 47 has cleared the shoulder 50, whereupon, in the mannerexplained, open passages have been provided from both pump chambers tothe source of supply, through which the liquid will be idly forced, backand forth, under pressure insufficient to unseat the valve 34. Torelieve the pressure in the ran1chamber, and lower the ram for removalor readjustment of the device, the cam 44 is still further rotated tofurther depress the tube 27 and cause the valve 30 to impinge againstthe top of the stem 35 and force the valve 34 off its seat, thus openinga passage, in the manner explained, from the pressure chamber to thereservoir or the source of supply, and leaving open the passages frompump chambers to said supplysource. As the cam 44 is returned to itsnormally inoperative position, the springs 29 and 41 serve to return thetube 27 and the collar 38, respectively, to their normally raisedpositions, restoring to the valves 30 and 34 their originally-describedfunctions.

In Fig. 2, I have illustrated the application of my invention to aself-contained double-pump hydraulic jack of what is known as thevertical type. In this type of jack, the ram 53 slides vertically in theramchamber 54 and is provided with a head 55 providing the reservoir 56for the liquid employed and a chamber for the pump-operating mechanism.In this type of jack the pump-block 57 is mounted within and forms apart of the ram. On account of the necessarily greater distance betweenthe top of the pump-block and the actuating mechanism in the head of thejack, instead of employing a short push-tube a longer tube 58 isemployed, the lower end of which rests upon the top of the tube 27,while the other end of the tube 58 is in coiiperative positionalrelation to the cam 59, which may be operated in a precisely similarmanner to the cam 44 in the construction shown in Figs. 1 and 3. In theconstruction shown in Fig. 2, the

spring 60 is sufliciently powerful to normally raise the tube 27 and thetube 58 resting thereupon. In this construction, furthermore, thechamber inthe valve-bore 25 below the valve 34 has a lower aperture 61open to the pressure-chamber 62 below the ram. Apart from the above,however, other features of the invention, in this construction, areidentical in all respects to those shown and described in connectionwith Figs. 1 and 3.

It will be apparent that the principles involved in my invention may aswell be em ployed in connection with other forms of pumps and jacks, andwith other arrangements of pumps or pistons, and other modifications ofminor details will doubtless readily suggest themselves to those skilledin this art. I therefore do not limit my invention to the specificconstruction, arrangement and applications herein shown and described.

I claim as new and desire to secure by Letters-Patent 1. A device forgenerating hydraulic pressure comprising a plurality of pumps, an equalnumber of valves, and valve-controlling means for rendering one of saidpumps inoperative.

2. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering one or more of said pumps inoperative.

3. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering one or all of said pumps inoperative.

l. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering said pumps successively inoperative.

5. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and means for rendering one of saidpumps inoperative and for relieving the pressure at the point ofapplication.

6. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and means for rendering one or more ofsaid pumps inoperative and for relieving the pressure at the point ofapplication.

7. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and means for rendering one or all ofsaid pumps inoperative and for relieving the pressure at the point ofapplication.

8. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering one of said pumps inoperative and for relieving the pressureat the point of application.

9. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering one or more of said pumps inoperative and for relieving thepressure at the point of application.

10. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valvecontrolling means forrendering one or all of said pumps inoperative and for relieving thepressure at the point of application.

11. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering one of said pumps inoperative, said means being furtheroperable to render inoperative more than one of said pumps.

12. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering one of said pumps inoperative, said means being furtheroperable to relieve the pressure at the point of application.

18. A device for generating hydraulic pressure comprising a plurality ofpumps, an equal number of valves, and valve-controlling means forrendering inoperative one of said pumps, said means being furtheroperable to render inoperative all of said pumps and, finally, torelieve the pressure at the point of application.

l-l. A device for generating hydraulic pressure comprising a pluralityof pumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering one of said pumps inoperative.

15. A device for generating hydraulic pressure comprising a plurality ofpumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering one or more of said pumpsinoperative.

1.6. A device for generating hydraulic pressure comprising a pluralityof pumps 1 having common actuating means, an equal number of valves, andvalve-controlling means for rendering one or all of said pumpsinoperative.

17. A device for generating hydraulic pressure comprising a plurality ofpumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering said pumps successivelyinoperative.

18. A device for generating hydraulic pressure comprising a plurality ofpumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering one or more of said pumpsinoperative and for relieving the pressure at the point of application.

19. A device for generating hydraulic pressure comprising a plurality ofpumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering one or more oi said pumpsinoperative and for relieving the pressure at the point of application.

20. A device for generating hydraulic pressure comprising a plurality ofpumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering one of said pumps inoperative,said means being further operable to relieve the pressure at the pointof application.

21. A device for generating hydraulic pressure comprising a plurality ofpumps having common actuating means, an equal number of valves, andvalve-controlling means for rendering one of said pumps inoperative,said means being further operable to render inoperative all of saidpumps and, finally, to relieve the pressure at the point of 1application.

22. A device for generating hydraulic pressure comprising two pumps, twovalves only, and valve-controlling means for rendering one of said pumpsinoperative.

23. A device for generating hydraulic pressure comprising two pumps, twovalves only, and valvecontrolling means for rendering one of said pumpsinoperative and for relieving the pressure at the point of application.

24. A device for generating hydraulic pressure comprising two pumps, twovalves only, and valvecontrolling means for rendaring one or both ofsaid pumps inoperative and for relieving the pressure at the point ofapplication.

25. A device for generating hydraulic pressure comprising two pumps, twovalves only, and means for rendering one of said pumps inoperative, saidmeans being further operable to relieve the pressure at the point ofapplication.

26. A device for generating hydraulic pressure comprising two pumps, twovalves only, and means for rendering one of said pumps inoperative, saidmeans being further operable to render both of said pumps inoperative.27. 1. device for generating hydraulic pressure comprising two pumps,two valves only, and means for rendering one of said pumps inoperative,said means being further operable to render both of said pumpsinoperative and still further operable to relieve the pressure at thepoint of application.

28. A device for generating hydraulic pressure comprising two pumps, twovalves only, and valve-controlling means for rendering one of said pumpsinoperative, said means being further operable to render both of saidpumps inoperative and still further operable to relieve the pressure atthe point of application.

29. In an hydraulic pump, the combination of a plurality of pistonshaving common actuating means, an equal number of valves, andcontrolling means for said valves for rendering ineii'ective theoperations of one of said pistons.

30. In an hydraulic pump, the combina tion of a plurality of pistonshaving common actuating means, an equal number of valves, andcontrolling means for said valves for rendering ineifective theoperations of one of said pistons and for relieving the generatedpressure.

31. In an hydraulic pump, the combina-.

tion of a plurality of pistons having common actuating means, an equalnumber of valves and controlling means for said valves for renderingineffective the operation of one or more of said pistons.

32. in an hydraulic pump, the combination of a plurality of pistonshaving common actuating means, an equal number of valves, andcontrolling means for said valves for rendering ineffective theoperations of one or more of said pistons and for relieving thegenerated pressure.

33. In an hydraulic pump, the combination of a plurality of pistonshaving common actuating means, an equal number of valves, andcontrolling means for said valves for successively renderingine'llective the operations of said pistons.

34:. In an hydraulic pump, the combination of a plurality of pistonshaving common actuating means, an equal number of valves, andcontrolling means for said valves for successively rendering ineffectivethe operations of said pistons and for relieving the generated pressure.

35. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-flow from both of the pump-chambers,a valve checking back-flow from the ultimate pressure chamber, and meansfor making said firstmentioned valve operable to check back flow fromone of said pump-chambers only.

86. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking bacleflow from both of the pump-chambers,a valve checking back-flow from the ultimate pressurechamber, and meansfor changing the location of said first-mentioned valve to checkback-flow from one of said pump-chambers only.

37. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-flow from both of the pump-chambers,a valve checking back-flow from the ultimate pressure chamber, and meansfor making said firstmentioned valve operable to check back-flow fromone of said pump-chambers only, said means being further operable torender said first mentioned valve wholly inoperative.

38. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-flow from both of the pump-chambers,a valve checking back-flow from the ultimate pressure chamber, and meansfor changing the location of said first-mentioned valve to checkbackfiow from one of said pump-chambers only, said means being furtheroperable to render said firstmentioned valve wholly inoperative.

39. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-fiow from both of the pump-chambers,a valve checking back-flow from the ultimate pressurechamber, and meansfor making said firstmentioned valve operable to check back-flow fromone of said pump-chambers only, said means being further operable tounseat said second-mentioned valve and open a passage from saidpressure-chamber to the source of liquid supply.

40. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-flow from both of the pump-chambers,a valve checking back-flow from the ultimate pressurechamber, and meansfor changing the location of said first-mentioned valve to checkback-flow from one of said pump-chambers only, said means being furtheroperable to unseat said second-mentioned valve and open a passage fromthe said pressure-chamber to the source of liquid supply.

41. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-flow from both of the pumpchambers,a valve checking back-flow from the ultimate pressurechamber, and meansfor making said firstmentioned valve operable to check back-flow fromone of said pump-chambers only, said means being further operable torender said first-mentioned valve wholly inoperative, and still furtheroperable to unseat secondmentioned valve and open a passage from saidressure-chamber to the source of liquid supp y.

42. A device for generating hydraulic pressure comprising two pumps, asingle valve normally checking back-fiow from both of the pump-chambers,a valve checking back-flow from the ultimate pressurechamber, and meansfor changing the location of said first-mentioned valve to checkback-flow from one of said pump-chambers only, said means being furtheroperable to render said first-mentioned valve wholly inoperative, andstill further operable to unseat said second-mentioned valve and open apassage from said pressure-chamber to the source of liquid supply.

4.3. A double-piston hydraulic pump having a single valve normallychecking backfiow from both pump-chambers, and means for controllingsaid valve to permit of back flow from one or both of said chambers.

44:. A double-piston hydraulic pump having a single valve normallychecking backflow from both pump-chambers, and means for varying theoperative position of said valve to permit of back flow from one or bothof said chambers. p

45. A double-piston hydraulic pump having two valves only in the passagefrom the source of liquid supply to the ultimate pressure chamber, andmeans for controlling one of said valves to render ineffectiveoperations of one or both of said pistons.

46. A double-piston hydraulic pump having two valves only in the passagefrom the source of liquid supply to the ultimate pressure chamber, andmeans for controlling one of said valves to render inefiectiveoperations of one or both of said pistons, said means being furtheroperable to open said passage.

47. A double-piston hydraulic pump having a fluid-passage not includingthe pumpchambers and providing the only means of communication betweenthe source of liquid supply and the ultimate pressure-chamber, twovalves only in said passage, and means for controlling one of saidvalves to render operations of one or both of said pistons ineffective.

48. A double-piston hydraulic pump having a fluid-passage not includingthe pumpchambers and providing the only means of communication betweenthe source of liquid supply and the ultimate pressure-chamber,

two valves only in said passage, and means for controlling one of saidvalves to render V operations of one or both of said pistonsineifective, said means being further operable to open said passage.

4-9. A double-piston hydraulic pump having a single fluid-passage fromthe source of liquid supply to the pressure-chamber, said passage notincluding the pump-chambers but communicating therewith, two valves insaid passage, and means for controlling one of said valves to renderoperations of one or both of said pistons ineffective.

50. In an hydraulic jack having a double pump, the combination of twovalves controlling flow from the source of liquid supply to the ultimatepressure-chamber, the first of which normally checks back-flow from bothof said pumps, and means for changing the relative position of saidfirst valve to check back-flow from one of said pumps only and therebyopen a passage from the other pump to said source of supply.

51. In an hydraulic jack having a double pump, the combination of twovalves controlling flow from the source of liquid supply to the ultimatepressure-chamber, the first of which normally checks back-flow from bothof said pumps, and means for changing the relative position of saidfirst mentioned valve to check back-flow from one of said pumps only andthereby open a passage from the other pump to said source of supply,said means being further operable to open passage from both pumps tosaid source of supply.

52. In an hydraulic jack having a doublepump, the combination of twovalves controlling fiow from the source of liquid supply to the ultimatepressure-chamber, the first of which normally checks back-flow from bothof said pumps, and means for changing the location of said first valveto check back-flow from one of said pumps only and thereby open apassage from the other pump to said source of supply, said means beingfurther operable to first render said valve wholly inoperative and thenpositively unseat the second valve.

53. In a double-pump hydraulic jack having a separate fluid-passage fromthe source of supply to the ultimate pressure chamber and a duct fromeach pumpchamber to said passage, the combination, with two valves insaid passage between which in their normal positions said ducts arelocated, and means for moving one of said valves to an operativeposition intermediate said ducts.

54. In a doublepump hydraulic jack having a fluidpassage from the sourceof supply to the ultimate pressure chamber and a duct from eachpump-chamber to said passage, the combination, with two valves in saidpassage between which in their normal positions said ducts are located,and means for moving one of said valves to an operative positionintermediate said ducts and there by opening a passage from one of thepumpchambers to said source of supply.

In a double-pump hydraulic jack having a fluid-passage from the sourceof supply to the ultimate pressure-chamber and a duct connecting eachpump-chamber with said passage, the combination, with two valves in saidpassage between which in their normal positions said ducts are located,of means for moving the first of said valves to an operative positionintermediate said ducts and thereby opening a passage from thefirst-pump-chamber to said source of supply, said means being furtheroperable to render said first valve wholly inoperative.

56. In an hydraulic jack having a fluidpassage from the source of liquidsupply to the pressurechamber and a duct connecting each pump-chamberwith said passage, the

combination, with two valves in said passage between which in theirnormal posimeans being further operable to open passages from both ofsaid pumps to said source of supply.

57. In an hydraulic jack having a fluidpassage from the source of liquidsupply to the pressure-chamber and a duct connecting each pumpchamberwith said passage, the combination, with two valves in said passagebetween which in their normal positions said ducts are located, of meansfor moving one of said valves to an operative position intermediate saidducts and thereby opening a passage from one of said pump-chambers tosaid source of supply, said means being further operable to openpassages from both of said pumps to said source of supply and stillfurther operable to unseat the other valve.

58. In an hydraulic jack having a double pump and correspondingpump-chambers, an individual fluid-passage from the source of liquidsupply to the pressure-chamber and ducts connecting said passage witheach of said pump-chambers, the combination of an initial inlet-valve, afinal outlet-valve, and means for moving said inlet-valve to anoperative position intermediate said ducts.

59. In an hydraulic jack having a double pump and correspondingpump-chambers, an individual fluicbpassage from the source of liquidsupply to the pressure-chamber and ducts connecting said passage'witheach of said pump-chambers, and combination of an initialinlet-valve, afinal outlet-valve, and means for moving said inlet-valve to anoperative position intermediate said ducts and thereby opening a passagefrom one pumpchamber to said source 01 supply.

60. In an hydraulic jack having a double pump and correspondingpump-chambers, an individual tluidpassage from the source of liquidsupply to the pressure-chamber and ducts connecting said passage witheach of said pump-chambers, the combination of an initial inlet-valve, afinal outlet-valve and means for moving said inlet-valve first to anoperative and then to an inoperative position intermediate said ducts.

61. In an hydraulic jack having a double pump and correspondingpump-chambers, an individual fluid-passage from the source of liquidsupply to the pressure-chamber and ducts connecting said passage witheach of said pump-chambers, the combination of an initial inlet-valve, afinal outlet-valve and means for moving said inlet-valve first to anoperative position intermediate said ducts, said means being alsooperable to render bothvalves inoperative.

'62. In a hydraulic jack having a double pump and correspondingpump-chambers, an individual fluid-passage from the source of liquidsupply to the pressure-chamber and ducts connecting said passage witheach of said pump-chambers, the combination of an initial inlet-valve, afinal outlet-valve, and means for moving said inlet-valve first to anoperative and then to an inoperative position intermediate said ducts,said means being also operable to render both valves inoperative.

68. In a double-piston hydraulic pump, a valve mounted in a movablecarriage'and be ing movable by said carriage to each of twoeffectivelydifl'erent locations, one in which said valve controlsback-flow from both of the pumps and one in which said valve controlsback-flow from one of said pumps only.

64. A double-piston hydraulic pump having a single valve normallychecking back flow from both pump-chambers, said valve being mounted ina movable carr'age and being movable by said carriage to each of twooperative and effectively different locations.

65. A double-piston hydraulic pump having a single valve normallychecking backflow from both pump-chambers, said valve being mounted in amovable carriage and being movable by said carriage to each of twooperative and effectively different locations, in one of which saidvalve checks back-flow from both of the pumps and one in which saidvalve checks back-flow from one of said pumps.

66. In a double-piston hydraulic pump, a valve mounted in a movablecarriage and being movableby said carriage to each of three effectivelydifferent locations, one in which said valve controls back flow fromboth of the pumps, one in which said valve controls back flow from oneof the pumps only, and one in which said valve is wholly ineffective.

67. A double-piston hydraulicpump having a single valve normallychecking back.

tions and to one in which said valve is wholly inoperative.

68. A double-piston hydraulic pump having a single valve normallychecking back flow from both pump chambers, said valve being mounted ina movable carriage and being movable by said carriage to each of threeeffectively different locations, in one of which said valve checks backflow from both of the pumps, in another of which said valve checks backflow from one of the pumps only, and in another of which said valve iswholly ineffective.

69. A pump having a valve-bore, a plurality of valves mounted therein,and a movable carriage for one of said valves said carriage beingprovided with means for establishing communication between thepump-chamber and said bore above said valve.

70. A double-piston pump having a valvebore, a plurality of valvesmounted therein, and a movable carriage for one of said valves providedwith means for establishing communication between one of thepumpchambers and said bore above said valve and for rendering said valveinoperative.

71. A double piston-pump having a valvebore, a plurality of valvesmounted therein, and a movable carriage for one of said valves providedwith means for establishing communication between one of thepumpchambers and said bore above said valve and for rendering said valveinoperative and for unseating the remaining valves in said bore.

In testimony of the foregoing, I have hereunto set my hand in thepresence of two witnesses. JAMES IV. NELSON. IVitnesses:

A. E. FARLEY,

Jae. MOORE.

